植物中抗胶质母细胞瘤天然产物的结构与活性

Tumor stem cells (TSCs) are widely accepted as a main cause of tumor chemo -resistance and radio-resistance, tumor migration and recurrence, and consequently the ideal target of therapy. Glioblastoma stem cell is the only type of tumor stem cell that can be cultured in vitro and keep stable in biological characteristics, gene expression pattern and genomic integrity for long time. Glioblastoma is extremely malignant with bad prognosis and little therapies. Natural products and their derivatives are mains constituent in antitumor drugs, and their structures diversity play a very important role in new drugs discovery. We established tumor stem cell-based high content screening technology (HCS) and animal model better mimicking the cancer etiology. More than 7000 defined fractions from medicinal plants were prepared and were subject of Glioblastoma stem cell screening. As a result, more than 100 fractions were active. Now we are going to identify the diverse active molecules by bioassay-guided isolation from the active fractions. 15-20 active compounds should be isolated, and then, the mechanism and in vivo evaluation on glioblastoma of 1-2 promising candidates from screening will be finished. Hopefully, the lead compounds for glioblastoma therapy agents can be expected by this project.

肿瘤干细胞是肿瘤发生发展、复发和转移的重要原因，应是肿瘤治疗的重要靶标。胶质母细胞瘤干细胞是能体外长期培养、且保持遗传学、生物学特性稳定的肿瘤干细胞，有利于药物筛选；胶质母细胞瘤恶性程度高、预后差，缺乏治疗药物。天然产物是抗肿瘤药物的重要源泉，相比植物总提物，其精制组分提高了有效成分的相对含量，提升了筛选命中率和发现活性化合物的可行性。.前期建立了抗肿瘤干细胞的筛选体系，以及符合人遗传学特征的胶质母细胞瘤动物模型。进一步筛选获得具有抗胶质母细胞瘤干细胞活性的云南特色药用植物有效组分100余个，显示出比现有活性化合物更多样的结构类型。.本项目拟研究资源植物有效组分库的化学成分，通过活性跟踪分离鉴定抗胶质母细胞瘤干细胞的活性化合物15-20个，完成其中1-2个重要分子的动物体内抗胶质母细胞瘤功能及其作用机制研究，以期发现治疗胶质母细胞瘤的新型先导分子。

完成了具有抑制脑胶质瘤干细胞活性的灯台叶（Alstonia scholaris）果实和叶、丽江唐松草(Thalictrum wangii )、腺毛唐松草（Thalictrum foetidum）、野扇花 (Sarcococca ruscifolia)、白骨壤(Avicennia marina)、八角枫（Alangium chinense）共6种植物系统的化学成分，共分离鉴定不重复化合物单体182个，其中新颖化合物35个，新骨架化合物7个。化合物结构类型涉及吲哚生物碱、异喹啉生物碱、C-19甾体、吡啶类生物碱及三萜类。.对分离得到的新颖结构及部分单体化合物开展了抗人脑胶质瘤干细胞GSC-3#，GSC-12#，GSC-18#和人正常胚胎肾细胞293T的活性筛选。结果显示16个单体化合物具有较好的抗胶质瘤干细胞的活性，其IC50值远小于替莫唑胺，与临床应用的抗肿瘤药物紫杉醇活性相当。对抗胶质瘤干细胞活性好的化合物scholarisine Q、alstoniasine、alstoniasidines A和B进行了作用机制研究。结果表明这四个化合物能显著抑制胶质瘤干细胞增殖，且可促进肿瘤坏死因子的表达而激发外源凋亡信号，从而诱导细胞发生凋亡，同时能显著破坏胶质瘤干细胞的自我更新及克隆扩增能力。.从丽江唐松草中获得的双苄基异喹啉生物碱neothalfine对多株肿瘤细胞系显示广谱活性，尤其是人结直肠癌细胞株（SW620），IC50与临床上抗肿瘤药多西他赛接近。作用机制研究表明其不仅可通过诱导细胞周期G2/M期停滞来抑制肿瘤细胞增殖，同时可降低SW620细胞线粒体膜电位提升caspase-3/7活性，进而引起线粒体功能障碍触发内在凋亡途径，致使SW620细胞凋亡。随后利用BALB/c-nude小鼠皮下移植瘤模型完成了neothalfine抑制肿瘤细胞增殖的体内活性评价。